Fundamental UNIX utilities
As a prelude to next week's scripting assignment, here is an
introduction to some commonly-used UNIX utilities (and hopefully
the beginning of understanding "the UNIX way"). You are encouraged
to read the man pages for each of these commands for more
details (many commands have lots more options than described below).
Simple text manipulation:
- cat filename1 [filename2 ...]
- (Con)catenate the named files and write to stdout. The
following commands typically take one or more filename arguments, or
read from stdin if no filename is specified.
- head -N, tail -N
- Show the first or last N lines of a file (10 if no N is given).
- cut -dchar -ffields
- Treating char as a delimiter, extract and output a field
or range of fields from each line of input. Example: cut -d:
-f6 /etc/passwd will print all the home directories in the
passwd file.
- tr fromlist tolist
- Transliterate characters (a character in fromlist is
changed to the corresponding character in tolist).
- sort
- Sort lines in input (has many options to specify things like sort
keys and different sorting orders).
- uniq
- Remove contiguous identical lines from input
- cmp file1 file2, diff file1 file2
- Check whether two files are different; diff shows
details about differences.
- find, xargs
- find (which has many options) descends directory
trees and outputs names of files that match specified criteria;
xargs is often used as a companion tool to find to
apply a command to a list of files it reads from its standard input.
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Steve VanDevender
Last modified: Thu Jul 26 14:28:27 PDT 2007